Hi Timo - I tried some dabbling with moi/mudbox about a year or so ago. I found the best results were obtained by setting angle to 40 and to export as triangles only. You then set the smoothing levels you need in mudbox. Then you can texture and paint using the mudbox toolset. Mudbox is way too sensitive on obj/fbx imports. 3DCoat is better for importing, but i can't get on with that as much as MudBox. I did not turn off UV co-ords though, so it might be worth a try, but i doubt it will help as MudBox never gave an error regarding UV's, it moaned about things like ...

too many polygons sharing a point/vertex
no support for importing quads or n-gons
and that smoothing applied was not of a recognised type such as Catmull-Clark

If those are the types of errors you are getting, then drop the density of the mesh generated by Moi to the bare minimum needed to keep coarse details.

Hope that helps you out a little

Martin Spencer-Ford